"Part of Me" is a song by American singer Katy Perry from Teenage Dream: The Complete Confection (2012), the reissue of her third studio album, Teenage Dream (2010). It was written by Perry herself, alongside Dr. Luke, Max Martin, and Bonnie McKee, with production handled by Dr. Luke and Martin, alongside Cirkut. The track was recorded at Conway Recording Studios, based in Hollywood, California, and Playback Recording Studios, based in Santa Barbara, California. The song was not included on the original edition of Teenage Dream because Perry felt that it did not fit the composition of the album. A demo of the song leaked online in late 2010, amid speculation that the lyrics were directed to the singer's ex-boyfriend Travie McCoy. "Part of Me" was re-worked and officially released as the lead single from The Complete Confection on February 13, 2012, through Capitol Records

A dance-pop and power pop record with electropop elements and a distinctive house beat, it has been compared to Perry's 2010 singles "Firework" and "California Gurls". Its lyrics describe a female protagonist who declares herself as unbreakable and strong following a break-up. Many critics theorized that the lyrics addressed Perry's divorce from British comedian, media personality and actor Russell Brand, although she stated it was not about him, since it was written in early 2010. The single's artwork was produced by art director Gavin Taylor and photographer Mary Ellen Matthews.

"Part of Me" was a commercial success. It was the twentieth song to debut at number one on the Billboard Hot 100, Perry's seventh number-one single on the chart, and her ninth consecutive number-one single on the Billboard Hot Dance Club Songs chart. Outside of the United States, "Part of Me" topped the charts in Bulgaria, Canada, New Zealand, and the United Kingdom, and has been certified diamond in Brazil while receiving multi-platinum certifications in Australia, Canada, New Zealand, and the United States. Marketing campaigns for Adidas and The Sims 3: Showtime have featured it.

An accompanying music video was filmed at the United States Marine Corps' Camp Pendleton in Oceanside, California. The video depicts Perry enlisting in the Marines following a break-up. It garnered generally positive reviews for Perry's "Girl power" message but drew criticism from feminist author Naomi Wolf, who denounced it as military propaganda. Perry debuted the first televised performance of the song at the 54th Grammy Awards and has also performed the song at the ECHO Awards, the 2012 Kids' Choice Awards, and American Idol.

I wrote 'Part of Me' two years ago and I always knew that 'Part of Me' was a special song, It feels like my life plays out with these songs. I feel like I'm in some kind of weird 'Truman Show' where I'm like, 'Why is this single appropriate now and it wouldn't have been appropriate then?' It's just so crazy.

Katy Perry wrote "Part of Me" with Dr. Luke, Bonnie McKee, and Max Martin during the 2010 Teenage Dream writing sessions, which also produced the Hot 100 number-one singles "California Gurls", "Teenage Dream" and "Last Friday Night (T.G.I.F.)." Cirkut also helped produce the track with Luke and Martin. Perry and McKee had been casual friends prior to Perry's request for her help with a song that Perry had been writing called "Part of Me". According to Rolling Stone, McKee stayed up all night writing the lyrics. When Perry was presented the song, she shouted "We're buying you a car!" by the time she heard the third line.

Perry recorded a demo of the track that leaked in full on December 30, 2010. The song was rumored to be a leftover cut from her Teenage Dream recording sessions, and fans speculated that the track might be included in an as-yet-unconfirmed re-release of the LP. This re-release was confirmed in January 2012, when Perry announced through her official website that the album would contain all twelve songs from the original album, plus three new songs and a remix, and would be released on March 26, 2012. Perry's press release stated: "This is the complete story of Teenage Dream. It was an incredible honor to tie the King of Pop's Billboard Hot 100 record, but I'm moving forward and had a few things left to get off my chest. So this is the complete special edition of my album for my fans."

On February 13, 2012, "Part of Me" received an official release as the lead single from the album's re-release. Perry had planned all along to release the song on the deluxe edition of the album rather than the original, as it did not fit that album's composition. On February 11, two days before its worldwide premiere, the song was leaked for a second time with a reworked production and slightly changed lyrics. "Part of Me" was released to most iTunes stores worldwide on February 18, 2012, following her performance at the 54th Grammy Awards. In the United States, "Part of Me" was sent to contemporary radio playlists on February 21, 2012. The song was released in England, Scotland, Wales, France, and Ireland on March 18, 2012 under the digital download and CD single formats. Perry revealed via Twitter that all profits raised from the sales of the single would be donated to MusiCares. The photograph by Mary Ellen Matthews that was used on the single cover was part of a photographic essay for Perry's appearance in episode 710 of the television program Saturday Night Live.